Olfactory responses are to be recorded from small twigs of the olfactory nerve, containing hyndreds to thousands of these small fibers, and quantified with the integrator, or moving-average technique, so prominently employed in taste studies. Response vs. concentration characteristics will be determined for selected odorants, including homologous chemical series. Slow potential responses (EOG's) from the olfactory mucosa and slow potential or wave responses from the olfactory bulb are to be related to the neural responses, if possible, from sites directly linked, anatomically. Experimental verification will be attempted of the belief that these relations can be manipulated with a number of procedures, which might be informative about stimulus and coding mechanisms. Unit primary and secondary responses will be studied in relation to the neural responses. Behavioral responses will likely be studied in collaboration with a Psychobiology colleague. Fish will be compared with air breathing animals such as turtles, frogs, birds and mammals. In catfishes, gustatory responses will be compared with olfactory responses to determine whether the exquisite sensitivities to amino acids are peculiar to this class of compounds and, if not, whether the overlap between taste (gustation) and smell (olfaction) is as extensive as for amino acids and their derivatives. BIBLIOGRAPHIC REFERENCES: Caprio, J., and D. Tucker. 1975. Taste and smell in an aquatic vertebrate: the chemoreception of amino acids in catfish. Neuroscience Abstracts 1:15. Wysocki, C. J., and D. Tucker. 1976. Preliminary investigations of specific olfactory deficits in mice. Behav. Genet. 6:122.